Add struct utils for validating JSON objects with optional values

src/index.test.ts

@@ -75,6 +75,7 @@ describe('index', () => {
         "createModuleLogger",
         "createNumber",
         "createProjectLogger",
+        "exactOptional",
         "getChecksumAddress",
         "getJsonRpcIdValidator",
         "getJsonSize",
@@ -115,6 +116,7 @@ describe('index', () => {
         "jsonrpc2",
         "numberToBytes",
         "numberToHex",
+        "object",
         "parseCaipAccountId",
         "parseCaipChainId",
         "remove0x",

src/json.test-d.ts

@@ -1,8 +1,11 @@
 /* eslint-disable @typescript-eslint/consistent-type-definitions */
 
+import type { Infer } from 'superstruct';
+import { boolean, number, optional, string } from 'superstruct';
 import { expectAssignable, expectNotAssignable } from 'tsd';
 
 import type { Json } from '.';
+import { exactOptional, object } from '.';
 
 // Valid Json:
 
@@ -134,3 +137,23 @@ class Foo {
 }
 const foo = new Foo();
 expectNotAssignable<Json>(foo);
+
+// Object using `exactOptional`:
+
+const exactOptionalObject = object({
+  a: number(),
+  b: optional(string()),
+  c: exactOptional(boolean()),
+});
+
+type ExactOptionalObject = Infer<typeof exactOptionalObject>;
+
+expectAssignable<ExactOptionalObject>({ a: 0 });
+expectAssignable<ExactOptionalObject>({ a: 0, b: 'test' });
+expectAssignable<ExactOptionalObject>({ a: 0, b: 'test', c: true });
+expectNotAssignable<ExactOptionalObject>({ a: 0, b: 'test', c: 0 });
+expectNotAssignable<ExactOptionalObject>({
+  a: 0,
+  b: 'test',
+  c: undefined,
+});

src/json.test.ts

@@ -1,4 +1,13 @@
-import { validate, assert as superstructAssert } from 'superstruct';
+import {
+  validate,
+  assert as superstructAssert,
+  is,
+  string,
+  union,
+  literal,
+  max,
+  number,
+} from 'superstruct';
 
 import {
   assert,
@@ -20,6 +29,8 @@ import {
   isJsonRpcSuccess,
   isPendingJsonRpcResponse,
   isValidJson,
+  object,
+  exactOptional,
   JsonStruct,
 } from '.';
 import {
@@ -39,6 +50,143 @@ jest.mock('superstruct', () => ({
   assert: jest.fn(),
 }));
 
+describe('object', () => {
+  it('validates an object', () => {
+    expect(
+      is(
+        {
+          foo: 'bar',
+        },
+        object({
+          foo: string(),
+        }),
+      ),
+    ).toBe(true);
+
+    expect(
+      is(
+        {
+          foo: 123,
+        },
+        object({
+          foo: string(),
+        }),
+      ),
+    ).toBe(false);
+  });
+
+  it('validates an object with exact optional values', () => {
+    expect(
+      is(
+        {
+          foo: 'bar',
+        },
+        object({
+          foo: exactOptional(string()),
+        }),
+      ),
+    ).toBe(true);
+
+    expect(
+      is(
+        {},
+        object({
+          foo: exactOptional(string()),
+        }),
+      ),
+    ).toBe(true);
+
+    expect(
+      is(
+        {
+          foo: 123,
+        },
+        object({
+          foo: string(),
+        }),
+      ),
+    ).toBe(false);
+
+    expect(
+      is(
+        {
+          foo: undefined,
+        },
+        object({
+          foo: exactOptional(string()),
+        }),
+      ),
+    ).toBe(false);
+  });
+});
+
+describe('exactOptional', () => {
+  const simpleStruct = object({
+    foo: exactOptional(string()),
+  });
+
+  it.each([
+    { struct: simpleStruct, obj: {}, expected: true },
+    { struct: simpleStruct, obj: { foo: undefined }, expected: false },
+    { struct: simpleStruct, obj: { foo: 'hi' }, expected: true },
+    { struct: simpleStruct, obj: { bar: 'hi' }, expected: false },
+    { struct: simpleStruct, obj: { foo: 1 }, expected: false },
+  ])(
+    'returns $expected for is($obj, <struct>)',
+    ({ struct, obj, expected }) => {
+      expect(is(obj, struct)).toBe(expected);
+    },
+  );
+
+  const nestedStruct = object({
+    foo: object({
+      bar: exactOptional(string()),
+    }),
+  });
+
+  it.each([
+    { struct: nestedStruct, obj: { foo: {} }, expected: true },
+    { struct: nestedStruct, obj: { foo: { bar: 'hi' } }, expected: true },
+    {
+      struct: nestedStruct,
+      obj: { foo: { bar: undefined } },
+      expected: false,
+    },
+  ])(
+    'returns $expected for is($obj, <struct>)',
+    ({ struct, obj, expected }) => {
+      expect(is(obj, struct)).toBe(expected);
+    },
+  );
+
+  const structWithUndefined = object({
+    foo: exactOptional(union([string(), literal(undefined)])),
+  });
+
+  it.each([
+    { struct: structWithUndefined, obj: {}, expected: true },
+    { struct: structWithUndefined, obj: { foo: undefined }, expected: true },
+    { struct: structWithUndefined, obj: { foo: 'hi' }, expected: true },
+    { struct: structWithUndefined, obj: { bar: 'hi' }, expected: false },
+    { struct: structWithUndefined, obj: { foo: 1 }, expected: false },
+  ])(
+    'returns $expected for is($obj, <struct>)',
+    ({ struct, obj, expected }) => {
+      expect(is(obj, struct)).toBe(expected);
+    },
+  );
+
+  it('supports refinements', () => {
+    const struct = object({
+      foo: exactOptional(max(number(), 0)),
+    });
+
+    expect(is({ foo: 0 }, struct)).toBe(true);
+    expect(is({ foo: -1 }, struct)).toBe(true);
+    expect(is({ foo: 1 }, struct)).toBe(false);
+  });
+});
+
 describe('json', () => {
   beforeEach(() => {
     const actual = jest.requireActual('superstruct');